These classical guitar fingerboard are slotted either with the compensated fret spacing used in the book and dvd, of the standard rule of 18 fret spacing. The compensated spacing provides a slightly better intonation up and down the guitar fingerboard. The boards are slotted to fit standard classical guitar fret wire. The boards come with a zero fret for easy trimming. 640mm scale length fingerboards are currently only available with compensated fret spacing.